Example of a testcontainer repository wrapped in a class

TestContainersExampleRepo.kt

package com.foo.bar

import io.r2dbc.spi.ConnectionFactories
import org.flywaydb.core.Flyway
import org.springframework.data.r2dbc.core.DatabaseClient
import org.testcontainers.junit.jupiter.Container
import org.testcontainers.junit.jupiter.Testcontainers

private const val username = "my_username"
private const val password = "my_password"
private const val databaseName = "my_database"
private const val schema = "my_schema"
private const val postgresImage = "postgres:9.6.10-alpine"
private const val migrationLocations = "filesystem:db/local-migration"

@Testcontainers
class FooBarRepository {
    @Container
    private val database = KotlinPostgreSQLContainer(postgresImage)
        .withUsername(username)
        .withPassword(password)
        .withDatabaseName(databaseName)!!

    fun migrate() {
        Flyway.configure()
            .dataSource(database.jdbcUrl, username, password)
            .locations(migrationLocations)
            .schemas(schema)
            .load()
            .migrate()
    }

    fun getDataBaseClient() = DatabaseClient.create(ConnectionFactories.get(getConnectionString()))

    private fun getConnectionString(): String {
        database.start()
        return "r2dbc:postgresql://$username:$password@localhost:${database.firstMappedPort}/$schema"
    }
}